Fluid filters



May 19, 1964 H. E. MILLINGTON FLUID FILTERS 4 Sheets-Sheet 1 Filed Dec.2, 1960 I/VVEN OR May 19, 1964 H. E. MILLINGTON FLUID FILTERS 4Sheets-Sheet 2 Filed Dec. 2, 1960 May 19, 1964 H. E. MILLINGTON FLUIDFILTERS 4 Sheets-Sheet 5 Filed Dec. 2, 1960 United States Patent Ofi ice3,133,847 Patented May 19, 1964 3,133,847 FLUID FILTERS Henry ErnestMillington, Crabtree, Plymouth, Devon, England, assignor to TecalemitLimited, Plymouth, Devon, England Filed Dec. 2, 1969, Ser. No. 73,233 8Claims. (Cl. 156-69) This invention relates to the construction offilter elements for the filtering of fluids and it is more particularlyconcerned with the construction of elements of the type in which theelement consists of one (or more) sheets of paper or other filtermaterial which is or are pleated or coiled and formed into an annular orother requ red shape and one or more of the edges of which is or aresealed so as to control the passage of the fluid and to ensure that itpasses through the filter material. Such filters include those of thestar type, in which a sheet of filter material is pleated and is securedin the form of an annular star between a pair of end caps to form thefilter element, and those of the spiral type, in which a sheet of filtermaterial is formed with a closed spiral which is secured between endcaps to form the element.

Another form of filter to which the invention is applicable is one inwhich a strip of filter material is pleated along transverse fold linesand is then folded in a fanlike manner to form a fan-type annularelement of a more or less disc-like form, in which the pleats radiatefrom the centre. In the case of this latter element, such as isdescribed in the specification of United States Patent No. 3,076,555,the edges of the filter material are secured to an inner tube and alsoto an outer sealing band, which parts may be made of paper or othersuitable material, to retain the shape of the element and to control thepassage of the fluid through the filter material, from one side of thefilter element to the other. According to one arrangement, which isdescribed in the last said specification, the outer sealing band may beformed of an elastic material, such as natural or synthetic rubber,which is fitted round and which presses against the edges of the pleatedfilter material.

When constructing filter elements of the star or spiral type, the usualmethod, which has been employed to secure the edges of the filtermaterial to the end caps, has been to use an adhesive or cement which isapplied to the inner faces of the end caps and into which the edges ofthe filter material are pressed before the adhesive or cement is causedor allowed finally to harden. Other methods of attaching the end capsinvolve the use of separate discs of an adhesive which are fitted in theend caps and which are caused to soften when the end caps are pressedagainst the edges of the filter material.

Such known or previously devised methods of sealing the edges of filtermaterial in fluid filter elements suffer from various limitations ordrawbacks, and it has been found the present invention provides animproved method for sealing such edges of filter elements relativelyless expensively and in fast mass production with less separate manualoperations, thus overcoming the drawbacks of previously proposedmethods.

According to the invention, in its broadest aspect, a method is providedfor forming a seal between adjacent edges of filter material in theconstruction of a fluid filter element, which comprises discharging,under pressure an adhesive substance in the form of a liquid onto thesaid edges, while maintaining relative movement between the point ofadhesive-discharge and said edges of the filter element, therebyproducing between the adjacent edges a seal which incorporates theadhesive when the latter has hardened.

According to one method of carrying out the invention, an adhesive issprayed onto the edges of the filter material in such a way, whilerotating said edges of the filter, and the adhesive being of suchconsistency, that it forms a continuous film, when it sets, whichconnects or bridges the spaces between the adjacent edges of the filterelement and prevents fluid when being filtered by the filter element,from passing between the latter edges, thereby ensuring that the fluidpasses through the filter material. The adhesive, due to its stiffnesswhen set, also fulfils the important function of maintaining the correctspacing between the pleats or turns of the filter material.

According to an alternative method, the adhesive is applied to the edgesof the pleated or spiral filter material by spraying, after which asealing member is pressed against the said edges and secured to thelatter by the action of the adhesive. The sealing member may be an endcap, in the case of filter elements of the star or spiral type, or itmay form the inner tube or the outer sealing band, in the case of filterelements of the fan type, such as are referred to above.

According to a modification of this latter method, the adhesive may besprayed simultaneously onto both the edges of the filter material andonto the surface of the end cap or other sealing member, before thelatter is pressed against the filter material.

The particular method and means used, by which the adhesive is sprayedonto the edges of the pleated material, including the angle of the sprayand the size and shape of the spray nozzles, are important to theproduction of the best results.

The present invention is also concerned with the provision of novel orimproved filter elements.

According, therefore, to a further feature of this invention, a fluidfilter element is provided comprising at least one sheet of filtermaterial which is formed into an annular shape and which includessealing members which are bonded to adjacent edges of the filtermaterial to ensure that the fluid being filtered passes through the saidmaterial, wherein one at least of the sealing members comprises acontinuous layer of an adhesive substance which has been sprayed ontothe edges of the filter material to form a continuous film sealing thespaces be tween the said edges.

The sealing members may take the place of conventional end caps, in thecase of filter elements of the star or spiral type, or of the inner tubeand/or outer band, in the case of fan-type elements.

Further features of the present invention will become apparent from thefollowing description.

Reference will be made to the accompanying drawings in which:

FIGURE 1 is an end elevational View, certain parts being omitted,showing one method of and apparatus for forming an end seal on a filterelement of the star type;

FIGURE 2 is a perspective view, largely diagrammatic, showing a modifiedmethod of forming a filter element of the star type;

FIGURE 3 is a detail view showing yet another modified method of forminga filter element;

FIGURE 4 is a detail view, broken-away, showing another form of end sealfor a filter element exemplifying the present invention;

FIGURE 5 is a diagrammatic view, partly broken-away, showing yet anothermethod of providing an end seal on a filter element;

FIGURE 6 is a view, partly broken-away, showing diagrammatically and insection a filter element of the fan type in which the folds of thepleats extend radially and showing the formation of the inner and outerseals at the ends of the pleats;

FIGURE 7 is a detail view showing a modification in a filter element ofthe type shown in FIGURE 6;

FIGURE 8 is a partly sectional and exploded view showing a filterelement of the fan type having an inner tube secured to the inner edgesof the pleated filter material;

FIGURE 9 is a perspective view partly broken-away showing a filterelement of the spiral type.

Referring first to FIGURE 1, this shows one method of spraying theadhesive on to the edges of the filter material, as applied to theconstruction of a filter element of the star type. This element isformed of a strip of filter material 2, such as paper, which is pleatedand formed into an annulus as shown, the ends of the strip beingfastened together in any suitable way to complete the annulus.

In order to form an end closure for the element, the pleated annulus ismounted on a rotary carrier having a core 3, on which the annulus isfitted and by which it is rotated in the direction of the arrow. Whilethe annulus is being rotated, the adhesive substance is sprayed on tothe end edges of the filter material and, in FIG- URE 1, this is shownas being done by means of two spray guns 4 and 5, two guns being usedfor speed in production although a single gun would sufiice.

Each of the spray guns includes a spray nozzle 11 which is supplied witha liquid adhesive through a pipe 6 and with air under pressure through apipe 7. The pipes shown at 8 are control lines leading from an externalcontrol (not shown) to control valves within the guns 4 and 5 so thatoperation of the control starts and stops the operation of the guns.

When the guns are operated adhesive supplied through the pipes 6 isentrained and atomised by the air delivered through the pipes 7 and isdischarged through the nozzles 21 in the form of fan-like sprays 9 at anoblique angle to the end of the filter element and laterally of the endedges thereof. Due to this angularity and position of these jets ofsprayed adhesive, the adhesive is sprayed on to the end edges of thepleated filter material, where it builds webs bridging the end edges ofthe pleats and eventually forms a continuous film or layer 10 closingthe spacing between said pleats. This layer 10 connects and forms a sealbetween the adjacent edges of the filter material 2 and, when allowed tobuild up to a proper thickness, renders it unnecessary to provide aseparate end cap.

It will be understood that, if a single application of the spray isenough, the layer 10 will be formed after the annulus has completed onlyone half of a revolution about the axis of the core 3, but if, as willgenerally be the case, a number of applications of the adhesive arenecessary or desirable the annulus may be caused to make one or morecomplete revolutions before the spray is cut oti and the annulus isremoved.

As an adhesive, it is preferred to use a substance which will retain adegree of resiliency after setting, such as natural or synthetic rubber(the latter being generally preferred, particularly when there is anypossibility of oil reaching the filter element or if the latter isintended for filtering oil). An example of a suitable material is anitrile synthetic rubber, such as that which is manufactured by TheGoodyear Tyre & Rubber Company and which is hold under the namePliobond. Another suitable synthetic rubber composition is that known asBoscoprene 2413 which is supplied by The BB. Chemical company.

It is also possible to use synthetic plastics for the adhesive, such asacrylic resins. One example incorporates n-butyl methacrylate. Thisprovides a transparent seal.

The nozzles n, through which the jets of adhesive are discharged againstthe end of the pleated annulus, are inclined at an angle to the plane ofthis end of the annulus, as can be seen from FIGURE 1. This angle is soselected that the adhesive adheres principally to the edges of thefilter material and only penetrates to a limited and controlled extentbetween the pleats. The angle will be determined by the nature andconsistency of the adhesive used and by the distances between the edgesof the pleats.

Experiments have shown that with annular, star-type filter elements ofthe conventional sizes, such as are usually used as oil or air filtersfor the engines of motor road vehicles, an average angle of about 65between the direction of the jets and the end plane of the filterelement produces the best results, although the angle may vary betweenlimits such as 60 to 65 or 60 to 70". In other cases, particularly whenthe distance between the edges of the pleats becomes large, the anglemay be further reduced to perhaps 55 or even less.

The application of the adhesive may be effected by rotating the pleatedannulus in front of (or beneath) a jet or jets, which is or are arrangedto spray the adhesive over the entire radial thickness of the pleatedmaterial, as shown in FIGURE 1, and small jets or nozzles With afan-like discharge may be used as shown in this figure. In certaincases, however, an elongated or slitlike nozzle may be used and anexample of this is shown diagrammatically in FIGURE 2.

In FIGURE 2, the pleated annulus 11 is shown as being mounted androtated beneath a slit-like nozzle, which is indicated diagrammaticallyat 12. This nozzle 12 is so designed as to discharge the adhesive evenlyover the end edges of the pleated material.

As has been indicated above, it is desirable, for best results, that theangle between the jet of adhesive and the plane, containing the edges ofthe pleated filter material, should be smaller where the distancesbetween the pleats are large (which they are near the outer edge of theannulus) than where these distances are smaller (as is the case nearerthe centre of the annulus); and FIGURE 2 shows one method of doing thiswhen a slit-like nozzle 12 is used. This is done by making the anglebetween the direction of the jet and the plane, containing the edges 13,greater near the centre than it is near the periphery of the annulus or,in other words, by making the angle of the jet with respect to thelongitudinal axis of the filter element less near the centre than nearthe periphery. If, for example, the angle a shown in FIGURE 2 is made 25while the angle b is made 35 the angle between the direction of the jetand the plane of the edges '13 will be 65, while the corresponding angleat the periphery, where the pleats are further apart, will be only 55.

An alternative method of achieving a similar result would be by using afiner form of jet which is reciprocated radially during the rotation ofthe pleated filter material, it being possible during this radialmovement to cause the angle of the jet relatively to the plane of theedges of the material to be varied. An example of how this may be doneis shown purely diagrammatically in FIGURE 3.

In this case shown in FIGURE 3, the pleated filter material 21 is shownas being rotated past a spray nozzle 22. This nozzle is shown as beingsupported by a pair of guides 23 and 24, along which it is reciprocatedby suitable means, not shown, during the rotation of the pleatedannulus, so as to distribute the adhesive over the radial thickness ofthe latter. By arranging the guide 24 at a suitable angle to the guide23, it is possible to ensure that the angle between the nozzle 22 andthe plane of the edges of the material is greater when the nozzle isnearer the centre, as shown in full lines, than when it is near theouter edge of the annulus, as shown in broken lines.

It may be remarked here that although, for the sake of convenience, theadhesive has been shown in FIG- URES 2 and 3 as being directeddownwardly on to the end of the pleated annulus, which is here shownhorizontal, it may generally be preferred to have the plane of the endvertical and the axis of the annulus horizontal, as in the case ofFIGURE 1.

In the filter elements which have been described so far it is intendedthat the closure of the ends of the spaces between the pleats should beeffected solely by the film of adhesive itself, but it is possible forthe adhesive to fulfil a further purpose as well. It may, for example,serve for attaching a label or the like. An example of this is shown inFIGURE 4. This shows a star type filter element having an annulus ofpleated filter material 31 to which an end coating 32 is applied byspraying. This may be done by one of the methods which have beendescribed with reference to FIGURES 1, 2 and 3. While the adhesive isstill soft or liquid a label 33 is applied, which label may carry anysuitable inscription or information. This label will be held in place bythe adhesive when the latter dries and it will strengthen and protectthe end of the filter element, although it will still be the adhesivewhich provides the seal to prevent fluid from escaping at the ends ofthe filter element.

In order to protect the label 33, it may be covered by means of a layer34 of transparent material. This layer could simply consist of a varnishor the like or it could be formed of a transparent adhesive. An exampleof the latter is an acrylic resin, such as n-butyl methacrylate.

The same or a similar acrylic resin adhesive could also be used to formthe actual sealing layer 32.

It is also possible, according to a further feature of this invention,to use an adhesive which is sprayed on to the edges of the filtermaterial to secure a separate end cap or other closure. This may be donein the manner which has been described for the label 33 of FIG- URE 4(but without the provision of a transparent covering layer 34). It is,however, preferred to utilise a method which is illustrated in FIGURE 5in which the adhesive is sprayed simultaneously on to the edges of thefilter material and on to the end cap, before the two are pressedtogether.

Referring to FIGURE 5, the pleated filter material is shown at 41, thepleated annulus being mounted on and rotated by a core 42 which issimilar to the core 3 of FIGURE 1. This core 42 carrying the filtermaterial is rotated by suitable means (not shown).

Supported spaced from but coaxial with the annulus 1 is an end cap 43,which may be formed of card or other suitable material. This issupported and rotated simultaneously with the pleated annulus by anysuitable means, a holder for the end cap being indicateddiagrammatically at 44.

A double nozzle 45 connected to a suitable spray gun (not shown) isfitted between the annulus 41 and the end cap 43 and while these arebeing rotated the adhesive is sprayed onto the edges of the filtermaterial, as shown at 46, and on to the inner face of the end cap, Whereit forms a film 47. The nozzle 45 is then withdrawn and the end cap isbrought against the end of the pleated annulus, where it is secured whenthe adhesive hardens.

FIGURE 6 shows the application of the invention to filter elements ofthe fan type, such as are referred to above, in which the folds of thepleats extend radially. In FIGURE 6 the pleated filter material isindicated at 51 and the drawing shows the simultaneous production of aninner sealing layer 52, which may take the place of a separate innertube, and of an outer sealing band 53, which may take the place of aseparate rubber or other band.

As is indicated purely diagrammatically in FIGURE 6, the inner layer 52may be formed by spraying the adhesive on to the inner edges of thefilter material using a nozzle 54, while the outer layer 53 may beformed in a similar manner using a nozzle indicated at 55.

As is clearly shown in the drawing, the outer layer 53 is so formed thatit includes upper and lower lips 56 and 6 57, which are shaped as shown.These both strengthen the filter element and also serve the very usefulfunction of providing a seal against the appropriate parts of the filtercasing in which the element is used.

In order to ensure the correct formation of these lips 56 and 57additional nozzles, such as those indicated at 58 and 59, may be used.

FIGURE 7 shows a modification of the filter element of FIGURE 6, in thatthe upper lip is formed with an integral raised bead 60. This may bedone by a suitable arrangement of the nozzle 58 and control of theamount of adhesive discharged by it.

The purpose of the raised bead 64) is to provide an improved seal withthe filter casing.

Instead of relying on the adhesive to take the place of an inner tube,it may be used to attach a separate inner tube, such as is indicated inFIGURE 8. In this case the pleated filter material 61 has the adhesivesprayed on to its inner edges 62, where it may form a continuous filmsimilar to layer 52 in FIGURE 6. While the adhesive of this film is wetthe inner tube 63 is fitted in position, where it is held by theadhesive. Similarly, if it is desired to use a separate outer band (notshown) this may be secured in position by means of adhesive sprayed onto the outer edges 64 of the filter material.

FIGURE 9 shows a filter element which is similar to that shown inFIGURES 1 and 2 except that the filter material 71, instead of beingpleated, is wound into a coil or spiral with the convolutions thereofspaced from each other. In this case the adhesive may be applied to theend edges 72 of the filter material by spraying. This may be done in amanner which may be similar to one of those which have been describedexcept that in this case the jet or jets used should be directedradially, either towards or way from the central axis of the filterelement.

I claim:

1. In constructing a filter element of sheet filteringmaterial formedinto a shape having, at least, one end thereof provided with a pluralityof adjacent edge portions which are spaced apart laterally from eachother, the method of forming a closure for said end of the filterelement to control the passage of fluid and to assure that the fluid, tobe filtered, passes through the filter material, which method comprisesdischarging under pressure drop lets of an adhesive substance in form ofa sprayed jet laterally of and onto said edge portions at an acute anglerelative to a plane extending from one adjacent edge portion to theother, while causing relative rotary movement of the jet of said sprayedsubstance laterally with respect to the said edge portions to build websof said substance bridging successively, during said relative movement,the spaces between said edge portions and embedding said edges therein;and continuing this operation until a layer is formed of desiredthickness to form a continuous unbroken cover closure for said end ofthe filter element with said edges bonded therein, when said adhesivesubstance has hardened.

2. A method as set forth in claim 1, where said laterally spaced edgeportions of the filtering element are at divergingly wider distancesapart along their length from one end of adjacent edge portions to theirother ends, said method being further characterized by arranging theacute angle, at which said jet of adhesive substance is sprayed to theplane extending between said edge portions, in a gradient of decreasingdegrees from the regions where the adjacent edges are relatively closesttogether toward the regions where the edges are farthest apart.

3. A method as set forth in claim 1, wherein the said laterally spacededge portions of the filter element are angulated relative to each otherso that the ends of said edge portions are at greater distance apart atone of their ends than at their other ends; and wherein said method ischaracterized by causing a relative reciprocating movement between saidjet spray of adhesive substance and said filter element the generaldirection in which said edges extend, during the aforesaid relativerotary movement of said filter element with respect thereto, and varyingsaid acute angle of said jet, during said reciprocating movement, togradually decrease the acute angularity of said jet as the distancebetween adjacent edge portions increases in one direction of saidreciprocating movement of said jet and to increase said acute angularityof said jet as the distance between adjacent edge portions decreases inthe other direction of said reciprocating movement of said jet.

4. A method according to claim 1, further characterized by applyingreinforcing members of sheet material to the outer exposed surface ofsaid closure of adhesive substance before said substance hardens,whereby said member becomes bonded thereto upon the hardening or settingof said adhesive.

5. A method as set forth in claim 1, including the step of aligning anannular reinforcing end-cap axially with the end of the filter elementto be sprayed; then rotating and spraying the face of said end-cap,opposing said end of said filter element, with said adhesive substancesimultaneously with and while said end of said filter is being sprayed,and then moving said cap into engagement with the sprayed end of saidfilter element with their adhesivebearing surfaces in adhering contact.

6. In constructing a filter element of sheet filtering-ma terial formedinto a pleated annular form with said pleats being substantially ofequal length and the distance varying between and along the end-edges ofadjacent pleats; the method of forming a closure at the end-edges ofsaid annular form to assure that fluid, to be filtered, passes throughsaid filter material when placed in a proper housing, said methodcomprising closing the spaces between the end edges of said pleats byspraying a jet of an adhesive substance at varying acute angles, withina range approximately 55 to 70, to and laterally of said end edges ofsaid pleats while rotating said filter element and said jet relativelyto each other, said acute angles being a gradient of lessening degreesfrom where the end-edges of the pleats are closest together toward wherethey are farthest apart, and conversely, thereby to form webs bridgingsaid spaces between the ends of said pleats until an unbroken continuousannular layer of said adhesive substance has built up upon and iscovering the area of said annular form defined by the end edges of saidpleats, and allowing said adhesive layer to harden to form a solidclosure with the end edges embedded in and bonded to said solid closure.

7. In constructing a filter element of sheet filtering-material formedinto a pleated annulus having the pleats extending radially thereof, themethod of forming a closure at the circumferences of said annulus toassure that fluid, to be filtered, passes through the filter material;said method comprising closing the spaces between the end edges of saidpleats at the inner and outer circumferences of said filter element byspraying jets of an adhesive substance toward the said circumferencesonto and laterally of said end edges of said pleats at varying acuteangles according to the varying distances between said end-edges whilecausing rotation of said circumferences and said jets relatively to eachother to form webs bridging said spaces between the ends of said pleatsuntil said circumferences of the annulus are provided with an unbrokencontinuous annular layer of said adhesive substance with said end edgesbonded into said layer.

8. A method according to claim 6, including similarly positioning andsimultaneously applying at least one jet of said adhesive onto andaround a corner of said end edges to form a lateral continuous cornerlip on at least one side edge of said pleats of said filter element andhomogeneous with the layer of said adhesive substance on the end-edgesof said pleats.

References Cited in the file of this patent UNITED STATES PATENTS1,457,625 Freyberg June 5, 1923 2,642,187 Bell June 16, 1953 2,732,031Rabbitt Jan. 24, 1956 2,739,916 Parker Mar. 27, 1956 2,843,218Kickhaefer July 15, 1958 3,025,963 Bauer Mar. 30, 1962 FOREIGN PATENTS747,780 Great Britain Apr. 11, 1956 OTHER REFERENCES Todd, W.D.:Plastisol Viscosity-Temperature Characteristics, reprint from ModernPlastics, September 1956, 13 pages.

Baird, D. K.: P. V. C. Paste, British Plastics, April 1948, pp. 167171.

Halofluorocarbon: Kel-F Dispersion, Bulletin H-JFCS (67.25) LP of theMinnestota Mining and Mfg. Co., received in the Patent Ofiice, Aug. 8,1958.

1. IN CONSTRUCTING A FILTER ELEMENT OF SHEET FILTERING, MATERIAL FORMEDINTO A SHAPE HAVING, AT LEAST, ONE END THEREOF PROVIDED WITH A PLURALITYOF ADJACENT EDGE PORTIONS WHICH ARE SPACED APART LATERALLY FROM EACHOTHER, THE METHOD OF FORMING A CLOSURE FOR SAID END OF THE FILTERELEMENT TO CONTROL THE PASSAGE OF FLUD AND TO ASSURE THAT FLUD, TO BEFILTERED, PASSES THROUGH THE FILTER MATERIAL, WHICH METHOD COMPRISESDISHCARGING UNDER PRESSURE DROPLETS OF AN ADHESIVE SUBSTANTCE IN FORM OFA SPRAYED JET LATERALLY OF AND ONTO SAID EDGE PORTIONS AT AN ACUTE ANGLERELATIVE TO A PLANE EXTENDING FROM ONE ADJACENT EDGE PORTION TO THEOTHER, WHILE CAUSING RELATIVE ROTARY MOVEMENT OF THE JET OF SAID SPRAYEDSUBSTANCE LATERALLY WITH RESPECT TO THE SAID EDGE PORTIONS TO BUILD WEBSOF SAID SUBSTANCE